The code, in two parts
You both need to know this cold. Card order for ties: rank first (ace low, king high), then suit in alphabetical order: clubs, diamonds, hearts, spades.
Part one: the first card gives the suit and a starting point. Among any five cards, at least two share a suit. Pick two of the same suit. Think of the ranks as a circle (ace, 2, 3 … queen, king, then back to ace). Going clockwise, one of the two is at most six steps ahead of the other. Hide the one that is ahead. Show the other one first. Your partner now knows the suit, and that the hidden card is 1 to 6 ranks above the first card.
Part two: the order of the other three gives the distance. Call the remaining three cards Low, Middle and High using the card order above. Lay them out after the first card in this order:
| Distance | Order of the last three cards |
|---|---|
| 1 | Low, Middle, High |
| 2 | Low, High, Middle |
| 3 | Middle, Low, High |
| 4 | Middle, High, Low |
| 5 | High, Low, Middle |
| 6 | High, Middle, Low |
Your partner counts that many ranks up from the first card, in its suit, wrapping from king to ace.
A worked example
The spectator hands you: 3♥, 10♥, 6♣, J♠, 8♦.
- Find a suit pair. 3♥ and 10♥. Counting up from 10♥: J, Q, K, A, 2, 3 is six steps. Counting up from 3♥ to 10♥ is seven. So 3♥ is the one ahead: hide it, and show 10♥ first.
- Rank the other three. 6♣ is low, 8♦ is middle, J♠ is high.
- Encode six. Distance 6 is High, Middle, Low.
- Lay out: 10♥, J♠, 8♦, 6♣, with 3♥ face down.
Your partner sees 10♥ first: hearts, start at ten. Then High, Middle, Low: six. Ten plus six, wrapping past king: 3♥.
Why it always works: with five cards and four suits, two must share a suit. Any two ranks on a circle of thirteen are at most six steps apart one way round. And three cards can be arranged in exactly six orders: one for each possible distance.
Practise together
- Drill the table until neither of you has to think about it. Deal five cards, encode, swap roles, repeat.
- Have the spectator hand you the cards, not lay them out. You need a few unhurried seconds to find the pair.
- Your partner should take their time. An instant answer looks like a signal. A slow, thoughtful one looks like mind reading.
On a date
This is the rare trick that needs two performers, which makes it the ideal thing to learn with the person you came with. Celeste would add that it is also a reliable way to find out whether you work well together under pressure.
Credit where due: Devised by mathematician William Fitch Cheney Jr. and published in Wallace Lee's Math Miracles (1950). We tested the code below on 100,000 random five-card hands; the partner named the hidden card every time.
Next: The key-card revelation